Vaccines induce protective immunity against numerous infectious diseases. However, current vaccines have limited efficacy against challenging infections like tuberculosis, malaria and HIV. Protein vaccines are safe but, typically, they induce weak T cell immunity when administered alone. Therefore, special attention is being given to adjuvants, which are enhancers of immunity, that mature antigen presenting immunostimulatory dendritic cells (DCs). Our goal is to study in humans the mechanism whereby synthetic adjuvants, acting on defined pattern recognition receptors (PRR), enhance T and B cell immunity. In preclinical studies, the investigators' laboratory has found in mice that poly IC and its analog poly ICLC are superior adjuvants for T cell mediated immunity relative to other agonists for PRR. In this study the investigators propose to study the safety and the innate immune responses to poly ICLC in multiple blood cell types, including three different subsets of DCs when administered subcutaneously or intranasally to healthy volunteers. Poly ICLC is a stabilized double stranded RNA which has been extensively studied in humans with a favorable safety profile.